Method of processing solvent-ex



REA arm Patented Oct. 5, 1954 UNITED STATES PATENT OFFICE John D.Bartleson, Cleveland, and Harvey E.

Alford, Amherst, -Ohio, assignors to The Standard Oil Company,Cleveland, Ohio, a corporation of Ohio N Drawing. Application August 27,1952, Serial No. 306,726

12 Claims.

This invention relates to a process of improving hydrocarbon baselubricants, and more particularly, to a process of treatingsolvent-extracted hydrocarbon lubricants with a small amount ofphosphorus pentasulfide followed by treatment with potassium hydroxideto form lubricants having improved properties and to the resultingimproved lubricants. The process is one of treating the entire body ofoil to be used as a lubricant as distinguished from the manufacture ofan additive for a lubricant.

Many of the commercially used lubricants are derived from hydrocarbonbase stocks which may be prepared synthetically or which may be obtainedfrom natural sources such as petroleum. In order to provide a lubricanthaving desirable characteristics, and particularly detergency, additivesusually must be included in the stock. Solvent-extracted oils, forexample, require the addition of additives to impart detergency thereto.

In U. S. Patent No. 2,560,546, dated July 17, 1951, to John D.Bartleson, a process of treating solvent-refined hydrocarbon baselubricating oil stocks has been described which imparts detergencythereto, thus avoiding the necessity of adding additives for thispurpose. According to the process outlined in that patent, thesolventrefined hydrocarbon lubricating oil stock is reacted with a smallamount of phosphorus pentasulfide and then with up to eight equivalentsof a base per mol of the sulfide used. Such lubricants have goodantioxidant and corrosion inhibition properties, and are suitable foruse under various conditions including high temperatures or highpressures, or both, as for instance, in an internal combustion engineoperating at high temperatures and in which the lubricant is in closecontact with metallic surfaces, metal compounds and high temperaturegases. They are also suitable for use in extreme pressure lubricents, e.g., in oils and greases containing the same, The resulting reactionproducts thus can be described as chemically finished 0r refinedimproved lubricants, relative to the untreated solvent-refinedhydrocarbon lubricating oil stock.

In accordance with the instant invention, it has been found that if thebase employed in reacting with the phosphorus pentasulfidetreatedsolvent-refined hydrocarbon lubricating oil stock is potassiumhydroxide, and an amount of base in excess of eight equivalents per molof the sulfide is used at a reaction temperature in excess of 325 F.,different products having especially desirable properties are obtained.Such products have a higher alkaline number, a higher ash content, andimproved storage stability, and in service show improved detergency and.anti-acid-wear properties. Thus the products are quite different, in anunexpected way. In contrast to the products prepared in accordance withU. S. Patent No. 2,560,546, the products of the invention tend to berelatively poorer in oxidation inhibition and corrosion inhibitionproperties, although still better than the untreated oil in theserespects. This, of course, can be corrected by addition of anyantioxidant.

The reaction of the solvent-refined hydrocarbon base stock with thephosphorus pentasulfide can be carried out as set forth in the aforesaidU. S. Patent No. 2,560,546 to John D. Bartleson. Thus, the reaction maybe conducted with direct admixture of the stock with the phosphoruspentasulfide, or, if desired, by their admixture in the presence of adiluent which may be subsequently removed. Generally a diluent is notnecesssary. The reaction usually is complete in about ten hours or lesstime; generally from one to two hours. The reaction time is a functionof the temperature, the amount of sulfide that is to react, the degreeof sub-division of the reactants,

3 the efficiency of mixing the reactants, and the like.

The hydrocarbon lubricating stock to which the process is applied is asolvent-extracted or solvent-refined oil, i. e., oils treated inaccordance with conventional modern methods of solvent-refinedlubricating oils. The oil may be a fluid hydrocarbon lubricating basestock having a viscosity at 100 F. of to 500 centistokes, such as isused as the base for SAE No. 10 to 50 oils. It may be obtained as adistillate or from synthetic materials, such as petroleum, and oilsproduced by cracking, polymerization, dehydrogenation, and the likemethods are also contemplated. The solvent-refining process is wellknown and generally involves a physical separation of impuritiesfromtheoil by extraction with a solvent. Uusually'the solvent selectecLsuch asfurfural, phenol, sulfur dioxide, etc., dissolves such constituents asaromatic, unsaturated and low viscosity index materials, and these areseparated. A clay treatment may follow, but while this is desirable, itis not essential. Where necessary, a separate propane or the likedeasphalating treatment may be used in conjunction with thesolvent-refining.

The solvent-refined hydrocarbon lubricating stock is reacted with thephosphorus pentasulfide in a ratio within the range from about 0.1 toabout 0.75% by weight, based on the weight of the stock, desirably about0.25 to about 0.60%, and preferably about 0.4 to about 0.6%. Higheramounts of the pentasulfide give products which are inferior to thehydrocarbon as to viscosity increase. Generally at least about 0.1%thereof should be used to achieve the desired result, although smalleramounts show some improvement.

The reaction of the solvent-refined hydrocarbon stock with thephosphorus pentasulfide can be carried out in the presence or absence ofair or in an atmosphere of inert or non-deleterious gas such asnitrogen. It may also be carried out under pressure, such as thepressure enerated when the reaction is carried out in a closed vesseldue to the liberation of gases in the course of the reaction.

During the reaction, nitrogen or other-inert gas can be bubbled throughthe reaction mixture. This assists in the removal and dissipation ofhydrogen sulfide, shifting the reaction towards the desired end productand thus shortening the time required to complete the reaction.

The refining temperature varies with the hydrocarbon stock. Generallythe treatment should be at least at 275 F. but should be below thetemperature at which the reaction product would be decomposed. Atemperaturein the range of about 300 to about 450 F. is preferred inmany cases. The reaction product preferably is centrifuged or filteredto remove by-products, sludge or other material. A volatile diluent, ifpresent, can be removed by evaporation or distillation.

The solvent-refined oil stock so treated is then treated with potassiumhydroxide. This reaction can be carried out at a temperature of about325 to 400 F., preferably 350 F. The sulfur content decreases withrising temperatures, while storage stability increases. Ash and alkalinenumber are at an optimum at 350 F. Ash and alkaline number are a measureof detergent properties. At temperatures above 400 F. the oil may beginto darken, which may be undesirable although it does not affect the goodqualities of the reaction product, and the alkaline number also drops.At temperatures below 325 F. the beneficial results 4 obtainable fromthe use of the higher quantities of the potassium hydroxide are notrealized.

If air is brought into the reaction mixture during the reaction ofpotassium hydroxide with the phosphorus sulfide-treated oil a largeramount of potassium hydroxide will react. Apparently the acidity of thematerial reacting with the po tassium hydroxide is increased possiblydue to oxidation, so that more acid groups are made available forreaction with potassium hydroxide. Therefore, although good results areobtained without introduction of air, to obtain the maximum effect fromthe use of large amounts of potassium hydroxide, i. e., maximumutilization of the potassium hydroxide, from the standpoint of alkalinenumber and ash weight of the product. it is desirable to introduce air.The amount of air is not critical, the improvement increasing inproportion to the volume of air used. Amounts up to about 8 liters ofair per grams of reaction mixture have been found to give satisfactoryresults, but more could be used if desired.

More than eight equivalents of potassium hydroxide are used per mol ofthe sulfide used in the solvent-refined stock, preferably 10.5equivalents. There is no critical upper limit to the amount of potassiumhydroxide except that more than will react with the solvent-refinedstock would not be used because it would be filtered off as an unreactedmaterial. Twelve equivalents have given excellent results, and sixteenequivalents have also been satisfactory.

Expressed on a weight basis, the amount of potassium hydroxide usedshould be more than two parts of potassium hydroxide to each part ofsulfide used in the solvent-refined stock, preferably three parts ofpotassium hydroxide to each part of sulfide, by weight. A 4:1 ratio hasbeen used and more than a 4:1 ratio of potassium hydroxide to sulfidecould be used, if desired.

In order to illustrate some of the advantages of the invention, but inno sense as a limitation thereof, the following specific embodiments areincluded.

Examples 1 to 23 In these examples the hydrocarbon stock was a blend of88.5 parts of 300 solvent-extracted neutral oil (300 SSU at 100 F.) and5 parts each of bright stocks of '78 and 250 SSU, respectively, at 210F. These stocks were refined by furfural extraction, methyl ethyl ketonedewaxing and clay treating, and are a good grade of solventrefined oil,available on the market, and typical of. such an oil.

The phosphorus pentasulflde was mixed with the hydrocarbon lubricatingoil in the amounts indicated in the following table, and reacted for thetime and at the temperature indicated, at atmospheric pressure in anopen vessel, While blowing nitrogen through the reaction mixture. Thebase used was potassium hydroxide in the dry-appearing flake formcontaining about 12% water, and therefore 88% active KOH. This wasreacted for the time and at the temperature indicated, while blowingnitrogen through the reaction mixture, which was in an open vesselexposed to the atmosphere. A11 weight per cents of potassium hydroxidein the table have been corrected to give the amount of active potassiumhydroxide available for reaction. The product analysis also is includedin the table. The examples identified by alphabetical letters are theintermediate phosphorus pentasulfide-oil reaction products, which weresubsequently neutralized by treatment with potassium hydroxide.

Reaction Mols oi Conditions Pwdm Analysis His Sta- Example PercentPercent KOH bility in No. P15 KOH per mol storage at of P 8 Time Temp.,Percent Percent Percent Alkaline F (Hrs) F. s Sulphur Phos. No.

None 1 300 O. 335 0.093 5 hrs. 1.06 10. 5 2 350 1. 33 0.26 0.095 4. 29 2mos 1. 06 10. 5 2 350 1.48 0.25 0.097 4. 22 2 mos 1.06 10. 5 2 350 1. 270.32 0.077 4. 59 2 mos None 1 300 0. 45 0.110 5 hrs. 1.06 10. 5 2 360 l.09 0. 30 0. 11 4. 94 2 mos None 1 300 5 hrs. 1.06 10, 5 2 350 0.8150.285 0. 1O 4. 14 2 mos None l 300 0.315 0.056 5 hrs. 1. 06 10. 5 2 3501.16 0. 215 0.053 3.88 2 mos None 1 300 0.335 0. 093 5 hrs. 0.7 7.0 2350 1.0 0. 235 0.095 2. 33 2 mos 1.06 10. 5 2 250 O. 0.26 0.073 1.01 2mos None l 300 0.385 5 hrs. 0.7 7 0 2 250 0.430 0.285 1.03 5 hrs. None 1300 0. 390 5 hrs. 0. 8.8 2 250 0.395 0. 325 0.82 5 hrs. 1. 06 10. 5 2250 O. 442 0.280 1.13 5 hrs. None 1 300 0.365 5 hrs.

1.06 7.0 2 350 1. 56 0. 345 4. 30 10 days 1. 58 10. 5 2 350 1.95 0. 3006. 83 2 mos None 1 300 0. 445 5 hrs. 2.1 10. 5 2 350 1. O. 390 4. 96 2mos None 1 300 .1 0. 415 5 hrS.

0. 7 7.0 2 350 1.04 0.295 2.16 2 mos. 2. 1 2 1 350 1. 84 0. 16 7. 28 1mo.

1 Blown with air during reaction.

Examples 1-6 and 16 are all oils treated with 10.5 or twelve equivalentsof KOH per mol of P285 and the amount of P285 used is 0.4%. These sevenoils show a high ash content, sulfur content, alkaline number and Hasstorage stability, indicating superior detergency and anti-wearproperties, compared to Examples 7 and 15 where only seven equivalentsof KOH are used per mol of P285. Examples '7 and 15 have goodantioxidant and corrosion inhibition properties, but Examples 1-6 and 16are better in detergency and anti-wear properties.

It will be noted that the reactions of KOH with the P285 treated oil inExamples 1-6 and 15' and 16 were carried out at 350 F. Examples 8-11 estash content and alkaline number of all of the products shown in thetable.

Example 14 shows the benefits obtainable at 0.8% P285, the upper limitof phosphorus pentasulfide.

It is readily. seen from the above data that Example 13 is the bestproduct of the group and the remainder, with the exception of Examples'7, 9, 12 and 15, are good equivalent products.

In the following, nitrogen and in some cases air are blown through thereaction mixture during the reaction of the phosphorus sulfide-oilreaction product with potassium hydroxide, and the reaction was carriedout in a closed vessel to exclude atmospheric air:

M 1 Reaction Conditions Lit Percent Percent 0 es ers Percent PercentPercent Alkaline No. 150 Example No. KOH per added per P785 KOH mole P 8Time Temp. Air Blow- 100 oil S] P Ash Total (hrs.) F.) ing 1 300 2 350NOBEL. O. 0. 095 0. 74 2. 67 8 2 350 41./100 g 4 0. 095 0. 088 1- 55 5-03 30 2 350 81.]100 g... 8 0.110 0. 088 1. 71 6. 22 30 2.4% KOH 1 300 2350 None 0. 225 0. 0. 94 4- 18 8 2 350 41/100 g.. 4 O. 175 0. 120 1. 896. 76 30 2 350 81./1U0 g 0. 220 O. 110 2. 07 7. 37 30 1 Corrected forsulfur in the base oil.

Examples 16, 19 and 21 were stable to liberation of H20 for one month atroom temperature. However, Examples 17, 18, 20, 22 and 23 were markedlysuperior in HzS stability at F. In

addition to improved HzS storage stability, air blowing also increasesash weight and alkaline number, showing a large amount of potassiumhydroxide has reacted, without appreciable less in sulfur andphosphorus. Thus detergency is improved while sulfur content remainshigh enough to obtain satisfactory corrosion inhibilents of KOH. Infact, Example 13 has the high- 75 tion.

Example 4 was subjected to the L-4 Chevrolet engine test. The testduration was 36' hours. The following results were obtained:

Varnish total 47.50

Skirt 9.25 Sludge total 47.50 Corrosion/half-shell mgs 98.1 Used oilproperties:

Vis. Inc 0.4

Per cent C5-Insols 0.1

Neut. No 0.99

Demerit rating 2.77-

This data shows that the oil gives satisfactory performance as an enginelubricating oil.

An engine wear test gave a 0.072 gram total ring weight loss for the oilof Example 6 ascompared with 0.1692 gram total ring weight loss for thebase oil. This demonstrates the high antiwear characteristics of thetreated oilof the invention.

The greatly improved characteristics of the chemically refined orfinished lubricants of the invention, particularly with respect to odorstability, detergency and anti-acid wear is especially noteworthy sincethese are major problems with conventional solvent-refined oils. Ifdesired, the improved lubricants of the invention can be used in blendstogether with other lubricants or other lubricant agents such as soap orthe like in a grease.

An antioxidant usually would be added in service to oils treated by theinvention. Any antioxidant can be used, such as dibutyl-p-cresol,sulfurized terpenes, dialkyl zinc dithiophosphates andtetramethyl-diamino-diphenyl methane.

An agent for improving the clarity of the oil'' may be included, e. g.,lauryl alcohol and the like. Agents for preventing foaming may also beincluded, e. g., tetraamyl silicate, an alkyl ortho-carbonate,ortho-formate or ortho-acetate, or a polyalkyl silicone oil.

In view of the foregoing disclosure, variations and modifications of theinvention will be apparent to those skilled in the art and it isintended to claim such variations and modifications broadly except as donot come within the scope of the appended claims.

We claim: 1

1. A method of processing solvent-extracted lubricating oil stockconsisting essentially of hydrocarbon material to yield an oil havingimproved properties in service which comprises treating said stock withan amount of phosphorus pentasulfide in the range of about 0.1 to about0.75% by weight, at a temperature in the range of about 275 to 450 F.,then with potassium hydroxide in an amount more than eight 8 equivalentsper mol of the phosphorus pentasulfide at a temperature of at least 325F.

2. The method of claim 1 wherein the sulfi'de-treated stock is reactedwith potassium hydroxide at a temperature within the range of about 325to about 400 F. in an amount in the range of more than eight to aboutsixteen equivalents per mole of the phosphorus pentasulfide.

3. The method of claim 2 wherein the stock is treated with an amount ofphosphorus pentasulfide in the range. of about 0.4'to about 0.6% andthen with an amount of potassium hydroxide in the range of more thaneight to about sixteen equivalents per mole of the phosphoruspentasulfide.

4. A lubricant obtained by the process oi! claim 1.

5. A lubricant obtained by the process of claim 2.

6. A lubricant obtained by the process of claim 3.

7. A method of processing solvent-extracted lubricating oil stockconsisting essentially of hydrocarbon material to yield oil havingimproved properties in service which comprises treating said stock withan amount of phosphorus pentasulfide in the range of about 0.1 to about0.75% by weight at a temperature in the range of about 275 to about 450F. and then with an amount of. potassium hydroxide of more than threeparts by weight to each part by weight of the phosphorus pentasulfide ata temperature of at least about 325 F.

8. A lubricant obtained by the process of claim 7.

9. A method in accordance with claim 7 in which the reaction withpotassium hydroxide is carried out while blowing air through thereaction mixture.

10. A lubricant obtained by the process of claim 9.

11. A method in accordance with claim 1 in which the reaction withpotassium hydroxide is carried out while blowing air through thereaction mixture.

12. A lubricant obtained by the process of claim 11.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,466,408 Funk Apr. 5, 1949 2,476,813 Buckmann July 19, 19492,483,571 Brennan Oct. 4, 1949' 2,560,546 Bartleson July 17, 1951

1. A METHOD OF PROCESSING SOLVENT-EXTRACTED LUBRICATING OIL STOCKCONSISTING ESSENTIALLY OF HYDROCARBON MATERIAL TO YIELD AN OIL HAVINGIMPROVED PROPERTIES IN SERVICE WHICH COMPRISES TREATING SAID STOCK WITHAN AMOUNT OF PHOSPHORUS PENTASULFIDE IN THE RANGE OF ABOUT 0.1 TO ABOUT0.75% BY WEIGHT, AT A TEMPERATURE IN THE RANGE OF ABOUT 275* TO 450*F.,THEN WITH POTASSIUM HYDROXIDE IN AN AMOUNT MORE THAN EIGHT EQUIVALENTSPER MOL OF THE PHOSPHOROUS PENTASULFIDE AT A TEMPERATURE OF AT LEAST325* F.